Wave Guiding of Far Infrared Radiation for the Jet Interferometer

The far infrared interferometer being designed to measure the electron density of the JET plasma will use waveguiding for beam propagation. An experimental 30 m long waveguide set-up is studied, using the 0,195 mm wavelength radiation of a DCN laser. The main characteristics of the guided beam are measured as a function of the angle of incidence. Transmissions up to 60 % are observed and the degree of polarization is kept to a high level in the case of a 60 mm diameter glass waveguide.